1. Field of the Invention
The present invention is directed to novel compositions, materials, methods of their use and methods of their manufacture that are generally useful as agents in the construction and building trades. More specifically, the compounds of the present invention can be used in construction and building applications that benefit from a relatively lightweight, extendable, moldable, pourable, material that has high strength and often improved insulation properties.
2. Description of the Prior Art
In the field of preparation and use of lightweight cementitious materials, such as so-called lightweight concrete, the materials that have been available to the trades up until now have generally required the addition of various constituents to achieve a strong but lightweight concrete mass that has a high homogeneity of constituents and which is uniformly bonded throughout the mass.
U.S. Pat. Nos. 3,214,393, 3,257,338 and 3,272,765 disclose concrete mixtures that contain cement, a primary aggregate, particulate expanded styrene polymer, and a homogenizing and/or a surface-active additive.
U.S. Pat. No. 3,021,291 discloses a method of making cellular concrete by incorporating into the concrete mixture, prior to casting the mixture, a polymeric material that will expand under the influence of heat during curing. The shape and size of the polymeric particles is not critical.
U.S. Pat. No. 5,580,378 discloses a lightweight cementitious product made up of an aqueous cementitious mixture that can include fly ash, Portland cement, sand, lime and, as a weight saving component, micronized polystyrene particles having particle sizes in the range of 50 to 2000 μm and a density of about 1 lb/ft3. The mixture can be poured into molded products such as foundation walls, roof tiles, bricks and the like. The product can also be used as a mason's mortar, a plaster, a stucco or a texture.
JP 9 071 449 discloses a lightweight concrete that includes Portland cement and a lightweight aggregate such as foamed polystyrene, perlite or vermiculite as a part or all parts of the aggregate. The foamed polystyrene has a granule diameter of 0.1-10 mm and a specific gravity of 0.01-0.08.
U.S. Pat. Nos. 5,580,378, 5,622,556, and 5,725,652 disclose lightweight cementitious products made up of an aqueous cementitious mixture that includes cement and expanded shale, clay, slate, fly ash, and/or lime, and a weight saving component, which is micronized polystyrene particles having particle sizes in the range of 50 to 2000 μm, and characterized by having water contents in the range of from about 0.5% to 50% v/v.
U.S. Pat. No. 4,265,964 discloses lightweight compositions for structural units such as wallboard panels and the like, which contain low density expandable thermoplastic granules; a cementitious base material, such as, gypsum; a surfactant; an additive which acts as a frothing agent to incorporate an appropriate amount of air into the mixture; a film forming component; and a starch. The expandable thermoplastic granules are expanded as fully as possible.
WO 98 02 397 discloses lightweight-concrete roofing tiles made by molding a hydraulic binder composition containing synthetic resin foams as the aggregate and having a specific gravity of about 1.6 to 2.
WO 00/61519 discloses a lightweight concrete that includes a blend of from around 40% to 99% of organic polymeric material and from 1% to around 60% of an air entraining agent. The blend is used for preparing lightweight concrete that uses polystyrene aggregate. The blend is required to disperse the polystyrene aggregate and to improve the bond between the polystyrene aggregate and surrounding cementitious binder.
WO 01/66485 discloses a lightweight cementitious mixture containing by volume: 5 to 80% cement, 10 to 65% expanded polystyrene particles; 10 to 90% expanded mineral particles; and water sufficient to make a paste with a substantially even distribution of expanded polystyrene after proper mixing.
U.S. Pat. No. 6,851,235 discloses a building block that includes a mixture of water, cement, and expanded polystyrene (EPS) foam beads that have a diameter from 3.18 mm (⅛ inch) to 9.53 mm (⅜ inch) in the proportions of from 68 to 95 liters (18 to 25 gallons) water; from 150 to 190 kg (325 to 425 lb) cement; and from 850 to 1400 liters (30 to 50 cubic feet) EPS beads.
U.S. Pat. No. 5,913,791 discloses a building block that has a cement-based attachment layer on one or both exterior surfaces of the block that receives and holds a penetrating fastener such as a nail, screw, staple, or the like. One cement-based layer contains water, cement, and expanded polystyrene foam beads in first proportions and a second exterior surface contains water, cement, and expanded polystyrene foam beads in second proportions different than the first proportions.
Generally, the prior art recognizes the utility of using expanded polymers, in some form, in concrete compositions, to reduce the overall weight of the compositions. The expanded polymers are primarily added to take up space and create voids in the concrete and the amount of “air space” in the expanded polymer is typically maximized to achieve this objective. Generally, the prior art assumes that expanded polymer particles will lower the strength and/or structural integrity of lightweight concrete compositions. Further, concrete articles made from prior art lightweight concrete compositions have at best inconsistent physical properties, such as Young's modulus, thermal conductivity, and compressive strength, and typically demonstrate less than desirable physical properties.
In many instances, the ability to utilize articles made of lightweight concrete is limited because such products include minute empty spaces where microbes are able to proliferate. Many of the microbes growing on such concrete articles products possess the ability to cause infection and contamination. Of particular concern are products designed for repeated human contact, such as dining tables, counter surfaces, bench tops and examination tables, walls and floors in hospitals, schools, restaurants, etc.
Therefore, there is a need in the art for lightweight concrete compositions that provide lightweight concrete articles having predictable and desirable physical properties and decreased microbial proliferation that overcome the above-described problems.